The present invention relates to a new and unique means for effecting the efficient collection and concentration of optical energy upon the surface of a fixed photovoltaic cell array. It is an important feature of this invention that such improved solar energy concentration is achieved without the necessity of extensive optical configurations, and sun-tracking or cooling mechanisms.
The use of photovoltaic devices to generate electrical energy is well understood. However, the primary obstacle to their use for generating significant amounts of electrical energy is their cost per peak watt. Current efforts to reduce construction costs of photovoltaic power systems include attempts to increase solar energy concentration on array surfaces by means of specular reflection and refraction. For example, in U.S. Pat. No. 3,427,200 of E. E. Lapin, et al., there is disclosed an apparatus that achieves solar energy concentration by means of specular reflection from polished, metallic sidewalls. Similarly, U.S. Pat. No. 3,873,829 of Evrard, et al., discloses an apparatus utilizing prisms to produce repeated total internal specular reflection of incident light. While the use of such means can substantially increase the output power of photovoltaic arrays, they require expensive optical configurations and complicated sun-tracking mechanisms. Furthermore, it is widely recognized that power efficiency of photovoltaic devices decreases with increase in temperature, necessitating some type of cooling mechanism where high concentration levels are encountered or sought. It is a unique feature of the present invention that moderate concentration ratios are utilized, therefore, eliminating the need for a cooling device.
The above-described problems are among the principal reasons why commercial use of photovoltaic cell arrays capable of high levels of optical energy concentration require special design and are costly to manufacture.